Correlation between functional outcome and alterations of aHKA, PCOR, and Caton-Deschamps index following image-based...

This study evaluated the relationship between functional outcomes and radiographic parameter changes in coronal and sagittal planes after robotic-assisted TKA in varus knees.

Between May 2020 and December 2022, all patients who underwent robotic-assisted total knee arthroplasty (RaTKA) using Functional Alignment technique (Mako, Stryker) and met predefined inclusion and exclusion criteria were enrolled in this study. A total of 115 patients (mean age 69.7 years; BMI 27.9; ASA 2.1) with varus knee morphology (defined as an arithmetic hip-knee-ankle angle [aHKA] < 0°) and complete datasets were included in the final analysis.For analysis pre- and postoperative full-length weight-bearing radiographs and lateral knee views were obtained, and the Medial Proximal Tibial Angle (MPTA) and mechanical Lateral Distal Femoral Angle (mLDFA) in the coronal plane, as well as the Posterior Condylar Offset Ratio (PCOR) and Caton-Deschamps -Index in the sagittal plane were assessed. Based on the differences between pre- and postoperative values of the key parameters, patients were classified into two groups: Collective A, showing no deviation from preoperative alignment, and collective B, exhibiting a deviation in at least one parameter according to predefined thresholds.Clinical outcome, and patient satisfaction 2 months postoperatively using validated patient-reported outcome measures (PROMs) were compared between the collectives.

No significant differences were observed between the collectives regarding demographics and preoperative clinical parameters. 47 patients were assigned to Collective A, 68 to Collective B. Collective A showed significantly better OKS (26.2 vs. 29.9; p = 0.037∗), EQ-VAS (75.0 vs. 67.2; p = 0.014∗), EQ-5D (0.87 vs. 0.80; p = 0.005∗), and ROM (+4.7° vs. -9.2°; p = 0,007∗), whereas FJS was non-significantly higher in A (44.5 vs. 34.1; p = 0.062).

Anatomic bony restoration in the coronal and sagittal plane was associated with better early outcomes. Even single-parameter deviations may impair results, underscoring the importance of accurate reconstruction in robotic TKA.